liverpool2044
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what is the effect of vagus nerve on sweat glands?

also if its a parasympathetic nerve why does it cause vasodilation as i thought this was done by the sympathetic side
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AortaStudyMore
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(Original post by liverpool2044)
what is the effect of vagus nerve on sweat glands?

also if its a parasympathetic nerve why does it cause vasodilation as i thought this was done by the sympathetic side
Sweating is a sympathetic response, not parasympathetic, and vasodilation is a parasympathetic response :P although technically, blood vessels are mainly under sympathetic control
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Reality Check
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(Original post by liverpool2044)
what is the effect of vagus nerve on sweat glands?

also if its a parasympathetic nerve why does it cause vasodilation as i thought this was done by the sympathetic side
The vagus has sympathetic as well as parasympathetic function. Sweating is an example of its sympathetic function.
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AortaStudyMore
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(Original post by Reality Check)
The vagus has sympathetic as well as parasympathetic function. Sweating is an example of its sympathetic function.
I don't think the vagus does cause sweating, sweating is a sympathetic response and parasympathetic fibres are craniocervical in origin, i.e. where the vagus originates. Any fibres causing sweating will originate in the thoracolumbar spinal cord, and realistically would only maybe hitch a ride in the vagus nerve, possibly in the vagosympathetic trunk idk
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liverpool2044
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i thought vagus was only known as a parasympathetic nerve, i realised the question regarded visceral blood vessels so i understand why that is dilation now, not sure about sweat glands i feel like they are almost always only innervated by the sympathetic. i know parasympathetic usually give increased secretion so does same apply with vagus nerve?
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(Original post by liverpool2044)
i thought vagus was only known as a parasympathetic nerve, i realised the question regarded visceral blood vessels so i understand why that is dilation now, not sure about sweat glands i feel like they are almost always only innervated by the sympathetic. i know parasympathetic usually give increased secretion so does same apply with vagus nerve?
I don't think vagus causes secretions, certainly not in the head
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liverpool2044
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(Original post by AortaStudyMore)
I don't think vagus causes secretions, certainly not in the head
just in general though for PS, things like salivation, sweating increase with cholinergic agonists? so acetylcholine is the main transmitter in the vagus nerve, i assume this works in a similar way in terms of secretion promotion?
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(Original post by liverpool2044)
i thought vagus was only known as a parasympathetic nerve, i realised the question regarded visceral blood vessels so i understand why that is dilation now, not sure about sweat glands i feel like they are almost always only innervated by the sympathetic. i know parasympathetic usually give increased secretion so does same apply with vagus nerve?
Actually lol I take that back, the vagus does cause secretion, in the stomach ... I forgot about that, sorry!
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AortaStudyMore
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(Original post by liverpool2044)
just in general though for PS, things like salivation, sweating increase with cholinergic agonists? so acetylcholine is the main transmitter in the vagus nerve, i assume this works in a similar way in terms of secretion promotion?
Yes you're right, unfortunately I did all this stuff last year so I'm a bit rusty haha, I know what the cranial nerves do in the head though, if thats of any use lol
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liverpool2044
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(Original post by AortaStudyMore)
Yes you're right, unfortunately I did all this stuff last year so I'm a bit rusty haha, I know what the cranial nerves do in the head though, if thats of any use lol
ahh okay thank you, no worries haha what course are you doing? yeahh that would be of great use, we've learnt about 1-3 and vagus, not too much about the others though
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AortaStudyMore
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(Original post by liverpool2044)
ahh okay thank you, no worries haha what course are you doing? yeahh that would be of great use, we've learnt about 1-3 and vagus, not too much about the others though
2nd year medicine, my exams are in just over a week... kms
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liverpool2044
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(Original post by AortaStudyMore)
2nd year medicine, my exams are in just over a week... kms
enjoying it? i plan on doing a post grad med after i finish my 3 year course
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(Original post by liverpool2044)
enjoying it? i plan on doing a post grad med after i finish my 3 year course
Yh it's good, but you have to put some serious work in
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(Original post by AortaStudyMore)
I don't think the vagus does cause sweating, sweating is a sympathetic response and parasympathetic fibres are craniocervical in origin, i.e. where the vagus originates. Any fibres causing sweating will originate in the thoracolumbar spinal cord, and realistically would only maybe hitch a ride in the vagus nerve, possibly in the vagosympathetic trunk idk
Umm, yes it does. Have a look here for a good refresher
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(Original post by Reality Check)
Umm, yes it does. Have a look here for a good refresher
Hahah, that link you sent me literally uses wikipedia as a source .. so it hasn't really proved anything
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(Original post by AortaStudyMore)
Hahah, that link you sent me literally uses wikipedia as a source .. so it hasn't really proved anything
You very confidently asserted that the vagus had no role in secretions, before retracting that because you forgot about its role in the GI tract. If you have a source which says that there is no role in sweating, or some other useful, verifiable information then it would be more helpful for the community for you to provide it, rather than mocking the posts of others.

Most of us don't claim to know everything there is to know about a particular topic, and rely on the help of others through referenced and verifiable information.
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(Original post by Reality Check)
You very confidently asserted that the vagus had no role in secretions, before retracting that because you forgot about its role in the GI tract. If you have a source which says that there is no role in sweating, or some other useful, verifiable information then it would be more helpful for the community for you to provide it, rather than mocking the posts of others.

Most of us don't claim to know everything there is to know about a particular topic, and rely on the help of others through referenced and verifiable information.
I didn't very confidently assert that the vagus had no role in secretions though? I said "I don't think" I've also never claimed to know everything? 🙄 sorry if I've come across as antagonistic, but I think it's fair to say I'm not the only one. Anyway, I have revision to do :/
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Jpw1097
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(Original post by liverpool2044)
just in general though for PS, things like salivation, sweating increase with cholinergic agonists? so acetylcholine is the main transmitter in the vagus nerve, i assume this works in a similar way in terms of secretion promotion?
That's because sweat glands are an exception to the rule. Yes, they are innervated by sympathetic fibres, however unlike most sympahetic fibres which are adrenergic (i.e. release noradrenaline), sympathetic fibres that innervate sweat glands are cholinergic (i.e. release acetylcholine). If I'm not mistaken, cholinergic sympathetic innervation is exclusive to sweat glands. Unlike most tissues/organs as well, which usually received dual inenrvation (parasympathetic and sympathetic), sweat glands are only innervated by sympathetic (cholinergic) fibres.

As for blood vessels, most blood vessels are only innervated by sympathetic fibres, however, whether they dilate or constrict depends on where it is in the body and what receptor it expresses. Therefore, it is the level of sympathetic activity determines the vessel diameter. Sympathetic stimulation will cause blood vessels supplying cardiac and skeletal muscle to dilate (increasing blood flow to skeletal and cardiac muscle) whereas most other blood vessels in the body (such as those supplying the GI tract) will constrict, allowing blood to be diverted from the GI tract, skin to the muscles. This is because blood vessels supplying cardiac and skeletal muscle express β2 adrenergic receptors whereas those supplying the skin, GI tract, etc. express α1 adrenergic receptors. However, blood vessels supplying the face and reproductive organs do have dual innervation. In this case, sympathetic stimulation causes vasoconstriction while parasympathetic stimulation will cause vasodilation.

Hopefully that helps
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liverpool2044
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(Original post by Jpw1097)
That's because sweat glands are an exception to the rule. Yes, they are innervated by sympathetic fibres, however unlike most sympahetic fibres which are adrenergic (i.e. release noradrenaline), sympathetic fibres that innervate sweat glands are cholinergic (i.e. release acetylcholine). If I'm not mistaken, cholinergic sympathetic innervation is exclusive to sweat glands. Unlike most tissues/organs as well, which usually received dual inenrvation (parasympathetic and sympathetic), sweat glands are only innervated by sympathetic (cholinergic) fibres.

As for blood vessels, most blood vessels are only innervated by sympathetic fibres, however, whether they dilate or constrict depends on where it is in the body and what receptor it expresses. Therefore, it is the level of sympathetic activity determines the vessel diameter. Sympathetic stimulation will cause blood vessels supplying cardiac and skeletal muscle to dilate (increasing blood flow to skeletal and cardiac muscle) whereas most other blood vessels in the body (such as those supplying the GI tract) will constrict, allowing blood to be diverted from the GI tract, skin to the muscles. This is because blood vessels supplying cardiac and skeletal muscle express β2 adrenergic receptors whereas those supplying the skin, GI tract, etc. express α1 adrenergic receptors. However, blood vessels supplying the face and reproductive organs do have dual innervation. In this case, sympathetic stimulation causes vasoconstriction while parasympathetic stimulation will cause vasodilation.

Hopefully that helps
fantastic thank you!
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(Original post by Jpw1097)
That's because sweat glands are an exception to the rule. Yes, they are innervated by sympathetic fibres, however unlike most sympahetic fibres which are adrenergic (i.e. release noradrenaline), sympathetic fibres that innervate sweat glands are cholinergic (i.e. release acetylcholine). If I'm not mistaken, cholinergic sympathetic innervation is exclusive to sweat glands. Unlike most tissues/organs as well, which usually received dual inenrvation (parasympathetic and sympathetic), sweat glands are only innervated by sympathetic (cholinergic) fibres.

As for blood vessels, most blood vessels are only innervated by sympathetic fibres, however, whether they dilate or constrict depends on where it is in the body and what receptor it expresses. Therefore, it is the level of sympathetic activity determines the vessel diameter. Sympathetic stimulation will cause blood vessels supplying cardiac and skeletal muscle to dilate (increasing blood flow to skeletal and cardiac muscle) whereas most other blood vessels in the body (such as those supplying the GI tract) will constrict, allowing blood to be diverted from the GI tract, skin to the muscles. This is because blood vessels supplying cardiac and skeletal muscle express β2 adrenergic receptors whereas those supplying the skin, GI tract, etc. express α1 adrenergic receptors. However, blood vessels supplying the face and reproductive organs do have dual innervation. In this case, sympathetic stimulation causes vasoconstriction while parasympathetic stimulation will cause vasodilation.

Hopefully that helps
Thanks - good explanation
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